The data based system, being service offer state posting manner, operational type database change manner and the operational type database machine decisive

摘要

PROBLEM TO BE SOLVED: To enable a controller to speedily deal with a fault when the fault has occurred in an active system database machine. SOLUTION: One of database machines 44 and 46 becomes an active system database machine and the other becomes a stand-by system database machine. Irrespective of an instruction from a control part 42, the active system database machine positively investigates possibility in its own service provision (whether a service can be provided or not). Then, the investigated result is reported to the control part 42. When the investigation result showing impossibility in the service provision for the active system database machine (presence of fault) is received from this machine, the control part 42 switches an active system and a stand-by system between the (present) active system database machine and the (present) stand-by system database machine.